KR100376157B1 - Magnetic recording media - Google Patents

Abstract

In the magnetic recording medium formed by providing a magnetic layer on one side of a base film made of an aromatic polyamide or an aromatic polyimide, the number of surface coarseness on the surface of the side on which the magnetic layer of the base film is formed is H2, The number of surface coarseness on the surface of the nonmagnetic layer side is H3.

The tensile Young's modulus (E20) in at least one direction at 20 ° C and the tensile Young's modulus (E100) in the same direction at 100 ° C

The present invention relates to a magnetic recording medium which satisfies the above requirements, and provides a magnetic recording medium having excellent durability, running characteristics, and output characteristics in a strict environment (especially high temperature).

Description

Magnetic recording media

Technical Field

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium, in particular magnetic recording medium having excellent running characteristics, durability, and output characteristics.

Background

In recent years, as a demand for increased outdoor use, miniaturization, and extended recording time of video cameras and a thin film for use as an auxiliary storage device for a computer, high density magnetics having excellent durability, running characteristics, and output characteristics in harsh conditions There is an increasing demand for recording media. Until now, as a magnetic recording medium, magnetic recording media formed by providing an oxide coated magnetic layer or a metal coated magnetic layer on a polyester film have been known (for example, Japanese Patent Application Laid-Open No. 61-26933, Japanese Patent Application Laid-Open No. 60-66319, etc.). ). As for the aromatic polyamide, an example in which a film having different Young Modulus (elastic modulus) in the longitudinal direction and the width direction is applied as a magnetic recording medium is disclosed in Japanese Patent Laid-Open No. 62-62424.

However, the above-described magnetic recording medium made of polyester film base or aromatic polyamide base has no problem at room temperature, but when used at high temperature, runability, poor output characteristics, or sound or image disappearing during repeated driving Problems such as occurrence have been suggested. This is considered to be because the heat resistance of the base film was insufficient, or the surface and running properties were not sufficient.

Moreover, as an example of the magnetic recording medium which defines the surface roughening process of a nonmagnetic material, as shown in Unexamined-Japanese-Patent No. 6-195679, the film back code roughness number is H2. There is an example of 50/100 cm2. In addition, it is H2 in JP-A-63-146941 publication 100 / 25cm2, Japanese Patent Application Laid-Open No. 59-203232 (H3-H2) An example of 200 pieces / mm 2 is shown.

However, Japanese Patent Application Laid-Open No. 6-195679 stipulates the number of coarse protrusions of the film backcoat, and the number of coarse protrusions on the magnetic surface side is not specified, which is insufficient to achieve sufficient output characteristics and runability. Further, in Japanese Patent Application Laid-Open Nos. 63-146941 and 59-203232, the base film is limited to a polyester film, the coarseness level is high, and the runability output characteristics when used at high temperature conditions deteriorate. There is a drawback.

In addition, the ratio between the Young's modulus at 90 ° C. (E90) and the Young's modulus at room temperature (ERT) is 1.0. E90 ／ ERT Although a magnetic recording medium using a base material specified in 0.6 is disclosed in Japanese Patent Application Laid-Open No. 64-53330, there is no regulation on the number of surface projections of the base material, and sufficient output characteristics cannot be obtained as a high density magnetic recording medium.

Also, Japanese Patent Application Laid-Open No. 63-28695 discloses an aramid film having a dimensional change rate of 5% or less at 200 ° C. for 5 minutes under a load of 1 kg / mm 2, but the carbon black is 10 to 40. It is different from the purpose of this specification because it contains% and its use is a thermal recording transcription | transfer body.

MEANS TO SOLVE THE PROBLEM As a result of earnestly examining the cause which this fault generate | occur | produces, it confirmed that it was the cause of the number of surface coarsening in the surface of the magnetic side and the nonmagnetic side in which the heat resistance and a magnetic layer of a base film are formed, and came to this invention.

Disclosure of the Invention

The present invention solves these problems and utilizes the excellent heat resistance and high rigidity of aromatic polyamides or aromatic polyimides, and also defines surface characteristics, thereby making it possible to drive, endurance, and output characteristics even under severe conditions such as high temperature and repeated driving. It is an object to provide this excellent magnetic recording medium.

That is, the present invention is a magnetic recording medium formed by providing a magnetic layer on one side of a base film made of an aromatic polyamide or an aromatic polyimide, and the surface coarseness number H2 and the nonmagnetic layer on the surface of the base film on which the magnetic layer is formed. Surface coarseness H3 from the surface of the side

And the base film has a tensile Young's modulus (E20) in at least one direction at 20 ° C. and a tensile Young's modulus (E100) in the same direction at 100 ° C.

It relates to a magnetic recording medium characterized by satisfying the.

Best Mode for Carrying Out the Invention

It is preferable that the aromatic polyamide of this invention contains 50 mol% or more of repeating units represented by the following general formula (I) or general formula (II), and it is more preferable that it consists of 70 mol% or more.

Where Ar ₁ , Ar ₂ , Ar ₃ are, for example,

And X and Y are

Etc., but is not limited thereto. In addition, some of these aromatic ring hydrogen atoms are substituted with substituents such as halogen groups (especially chlorine), nitro groups, C ₁ -C ₃ alkyl (especially methyl groups), and C ₁ -C ₃ alcohol groups. Also included are those in which hydrogen in the amide bonds constituting the polymer are substituted with other substituents. In view of properties, it is preferable that the above-mentioned aromatics are bonded to the Para position, since the polymers which occupy 50% or more, preferably 70% or more of the total aromatics have high film stiffness and good heat resistance. In addition, in view of reducing the water absorption, a polymer in which the aromatic ring in which a part of the aromatic ring-shaped hydrogen atom is substituted with a halogen group (particularly chlorine) is 30% or more of the total is preferable.

The aromatic polyamide of the present invention contains 50 mol% or more of the repeating units represented by the general formula (I) and / or the general formula (II), and less than 50 mol% is copolymerized or trended with other repeating units. It does not matter.

The aromatic polyimide in the present invention includes at least one aromatic ring and an imide ring in the repeating unit of the polymer, and contains 50 mol% or more of the repeating unit represented by the general formula (III) and / or the general formula (IV). It is preferable to, and it is more preferable to contain 70 mol% or more.

Here, Ar ₄ and Ar ₆ contain at least one aromatic ring, and the two carbonyl groups forming the imide ring are bonded to the adjacent carbon atoms in the aromatic ring. Ar ₄ is derived from aromatic tetracarboxylic acid or this anhydride. Typical examples include the following.

Where Z is

And the like.

Ar ₆ is derived from carboxylic anhydride or a halide thereof. Ar ₅ , Ar ₇ is, for example

And X and Y are

Etc., but is not limited thereto.

In addition, some of these aromatic ring hydrogen atoms include those substituted with a substituent such as a halogen group (particularly chlorine), a nitro group, an alkyl group (particularly a methyl group) of C1 to C3, an alcohol group of C1 to C3, etc. Moreover, the thing in which hydrogen in the amide bond which comprises a polymer is substituted by another substituent is also included.

The aromatic polyimide of this invention contains 50 mol% or more of repeating units represented by general formula (III) and / or general formula (IV), and less than 50 mol% does not interfere even if other repeating units are copolymerized or mixed. There is no

The aromatic polyamide and the aromatic polyimide of the present invention may be mixed with a lubricant, an antioxidant and other additives to the extent that the physical properties of the film are not impaired.

In the magnetic recording medium of the present invention, the surface coarseness number H2 of the surface of the side on which the magnetic layer of the base film is formed,

Need to be. More preferably H2 30, more preferably H2 20. If H2> 50, the surface property as a magnetic recording medium deteriorates, a phenomenon in which a sound or an image is erased arises, and it becomes unsuitable as a high density magnetic recording medium.

In the magnetic recording medium of the present invention, the surface coarsening number H3 of the surface of the base film on the non-magnetic layer side,

Need to be. More preferably 2 H3 70 more preferably 2 H3 50. If H3 < 2, the contact resistance with the guide roll or the like as the magnetic recording medium becomes large, and the running performance is lowered. If H3> 100, the coarseness is transferred to the magnetic layer when it is made as a magnetic tape, or the coarseness is affected by the surface treatment on the magnetic layer side during the calendering process in the charting process in manufacturing the coated magnetic recording medium. It is not preferable because it may cause a phenomenon that the sound or image may be erased.

In the magnetic recording medium of the present invention, the number of surface coarsenings on the surface of the side on which the magnetic layer of the base film is formed is H1.

Is preferably. More preferably H 70, more preferably H1 If it is 50, since the outstanding electron conversion characteristic appears, it is preferable. In addition, the magnetic recording medium of the present invention has a tensile Young's modulus (E20) of at least one direction at 20 캜 of the base film.

Need to be. More preferably E20 900 kg / mm 2, more preferably E20 1000 kg / mm 2 is required. Since the magnetic recording medium of the present invention is often used as a thin film in response to a request for thinning the magnetic recording medium, a high Young's modulus (E20) can be used to withstand the tension applied during tape travel or stop / start. 800 kg / mm 2). If the Young's modulus is lower than this, the tape is stretched and recording reproducibility is reduced. The base film has a high Young's modulus 800 kg / mm 2) can withstand the tension generated during the formation of the magnetic recording medium such as the coating layer forming back coat layer forming step, which is advantageous in processing.

In addition, the magnetic recording medium of the present invention has an elongation Young's modulus (E20) of at least one direction at 20 캜 of the base film.

Although it does not interfere even if it is stretched in the longitudinal direction or the diagonal direction, it is generally tensioned in the longitudinal direction or the width direction. The degree of tension is not particularly limited, but considering the properties such as elongation and resistance to tearing, tensile Young's modulus in the longitudinal direction (EMD) and tensile Young's modulus in the width direction (ETD),

It is practical to be in the range of.

In the magnetic recording medium of the present invention, the base film has a Young's modulus (E20) in at least one direction at 20 ° C and a tensile Young's modulus (E100) in the same direction at 100 ° C.

Need to be. More preferably 0.6 E100 / E20, More preferably, it is 0.7 E100 / E20. If it is 0.5> E100 / E20, when used under high temperature conditions, the thermal elongation is caused by the decrease in the rigidity of the tape, and the recording reproducibility decreases. If the Young's modulus decreases at high temperature (0.5) E100 / E20), since the dimensional change of the tape is suppressed in the drying step after coating of the magnetic layer in the manufacture of the coated magnetic recording medium and the metal thin film deposition step in the production of the deposition type magnetic recording medium, It is advantageous.

In addition, the magnetic recording medium of the present invention preferably has a dimensional change rate at 100 ° C. for 10 minutes when the load of 1 kg per 1 mm 2 in the longitudinal direction of the base film is 2% or less. More preferably, it is 1,5% or less, More preferably, it is 1.0% or less. Since the magnetic recording medium of the present invention is often used as a thin film according to the necessity of thinning the magnetic recording medium, when the dimensional change rate is 2% or less, when used at a high temperature, it may occur during tape travel or at a stop / start. The expansion and contraction of the tape caused by the tension is suppressed, thereby improving the recording reproducibility. In addition, since the base film has high dimensional stability (2% or less) with respect to external force, the drying process after formation of the coating layer in manufacturing the coated magnetic recording medium or the deposition of a metal thin film in manufacturing the deposited magnetic recording medium. Since the dimensional change of the tape in the process is suppressed, it is also advantageous in processing.

The present invention is a magnetic recording medium in which a magnetic layer is provided on one side of the base film described above.

As a method of forming the magnetic layer, there are dry methods such as a wet method, a vapor deposition method, a spotting method, an ion plating method, and the like, in which a strong magnetic powder is applied onto a base film using various binders. Although it is not specifically limited, in this specification, it demonstrates taking a wet method as an example.

Although the kind of magnetic powder which becomes a magnetic substance is not specifically limited, Ferromagnetic powder, for example, chromium oxide, Fe, Co, Fe-Co, Fe-Co-Ni, Co-Ni etc. which are to be oxidized is used preferably. .

The magnetic powder may be a magnetic coating using various binders, but thermosetting resin binders and radiation curing binders are preferable, and other additives may be a dispersant, a lubricant, an antistatic agent, or the like. For example, a binder made of vinyl chloride, vinyl acetate, vinyl alcohol copolymer, polyurethane pure polymer, and polyisocyanate can be used.

In order for the magnetic recording medium of the present invention to have an appropriate roughness, it is preferable that particles are present in the base film. Examples of the particles include inorganic particles such as SiO ₂ , TiO ₂ , Al ₂ O ₃ , CaSO ₄ , BaSO ₄ , CaCO ₃ carbon black, zeolite, and other metal fine powders, silicon particles, polyimide particles, and crosslinked (birdged) particles. Organic polymers such as copolymer particles, crosslinked polyester particles, and teflon particles, but inorganic particles are more preferable in terms of heat resistance, and the average primary particle diameter of the particles contained in the film of the present invention is 0.005. It is-5 micrometers, Preferably it is the range of 0.01-2 micrometers, In this case, since both the electron conversion characteristic and run | running property become favorable, it is preferable. The content of particles contained in the base film of the magnetic recording medium of the present invention is 0.01 to 5 wt%, preferably 0.05 to 3 wt%. When the content of the particles is less than the above-mentioned range, the running property of the film is poor, and conversely, the electron conversion property tends to be poor, even if at most.

As the base material of the magnetic recording medium of the present invention, not only a film but also a single layer film may be used, but a laminated film may be used. When used as a laminated film, the surface coarseness number of the present invention is H2 on the surface on which the magnetic layer is provided. The surface prescribed by 50 is laminated so that the surface becomes a surface, and in the nonmagnetic layer, the number of surface coarseness of the present invention is 2 H3 When the surface prescribed | regulated by 100 is laminated | stacked so that it may become a surface, both driving | running property and an electron conversion characteristic become favorable and it is preferable. The base film of the magnetic recording medium of the present invention and the base layer portion (film constituent parts other than the laminated base film of the present invention) laminated here may be the same kind or different. Particles may be contained in at least one layer constituting this base layer portion, and the average primary particle size and content of the particle types of particles are preferably used in the film of the present invention. It is preferable that the diameter of the particles in the base layer portion is larger than the diameter of the particles in the base film of the present invention in which the base film surface has a moderate degree of undulation, and the tape running property is further improved.

In the magnetic recording medium of the present invention, the thickness of the base film is preferably 0.5 to 50 µm, more preferably 1 to 20 µm, and more preferably 2 to 10 µm. It is desirable to have excellent runability and electron conversion characteristics.

The elongation in at least one direction of the base film in the magnetic recording medium of the present invention is 10% or more, more preferably 20% or more, even more preferably 30% or more. It is expected to have.

If the moisture absorption of the base film in the magnetic recording medium of the present invention is 5% or less, more preferably 3% or less, and more preferably 2% or less, the dimensional change of the tape due to the change in humidity is small, and the excellent electron conversion characteristics are achieved. It is preferable because it can maintain.

When these characteristics are laminated | stacked, it is preferable to be satisfied also about a laminated | multilayer film.

The manufacturing method of the present invention will now be described, but is not limited thereto.

First, in the aromatic polyamide, when obtained from an acid chloride and a diamine, it is N-methylpyrrolidone (NMP: N-methyl-pyrolidone), dimethyl acetamide (DHAc: dimethyl acetamide), dimethyl formamide (DMF: Dimetyl formamide). In the non-protic organic polar solution, such as a solution polymerization or by interfacial polymerization using an aqueous medium. The polymer solution is produced by the addition of hydrogen chloride when the acid chloride and diamine are used as monomers. Inorganic neutralizers such as calcium hydroxide, calcium carbonate and lithium carbonate, or organic neutralizers such as ethylene oxide, propylene oxide, ammonia, triethanolamine, triethanolamine, diethanolamine and the like are used. In addition, the reaction of isocyanate and carboxylic acid is performed in the presence of a catalyst in an aprotic organic polar solution.

These polymer solutions may be used as they are as a film-forming solution, or they may be separated into a single hole and then re-dissolved in an organic solvent or an inorganic solvent such as sulfuric acid to prepare a film-forming solution.

In order to obtain the aromatic polyamide film of the present invention, it is preferable that the intrinsic viscosity of the polymer (the value measured at 30 ° C. by making a solution of 0.5 g of polymer and 100 ml of sulfuric acid) is 0.5 or more.

In some cases, inorganic salts such as potassium chloride, magnesium chloride, lithium chloride, lithium acetate, etc. may be added to the film forming solution. The polymer concentration in the liquid for forming the film is preferably about 2 to 40 wt%. On the other hand, the solution of aromatic polyimide or polyamic acid is obtained as follows. That is, the polyamic acid reacts tetracarboxylic dianhydride and aromatic diamine in an aprotic organic polar solution such as N-methylprolidone (NMP), dimethylacetamide (DMAc) or dimethylformamide (DMF). I can prepare it. Moreover, aromatic polyimide can be manufactured by heating the solution containing polyamic acid mentioned above, or adding imidation agents, such as a pyridine, to obtain polyimide powder, and melt | dissolving this again in a solvent. The polymer concentration in the stock solution for forming the film is preferably about 5 to 40 wt%.

Examples of the method for adding the particles include a method in which the particles are sufficiently suspended in a solvent beforehand, used as a solvent for polymerization or a diluent, or a method for directly adding after preparing a film forming undiluted solution.

The film forming undiluted solution prepared as mentioned above is made into a film by what is called a solution film forming method. The solution film forming method includes a dry wet method, a dry method, a wet method, and the like, and may be formed by any method. Here, the dry wet method will be described as an example.

In the case of making a film by the wet-and-dry method, the stock solution is extruded from a cap on a support such as a drum or a caterpillar to form a thin film, and then the solvent is dispersed from the thin film layer and dried until the thin film has self-maintainability. Drying conditions are the range of room temperature-220 degreeC within 60 minutes, Preferably it is the range of room temperature-200 degreeC. If the drying temperature exceeds 220 ° C., the surface coarsening may increase H 2 and exceed the scope of the present invention. In addition, H3 can be controlled within the scope of the present invention by controlling the surface defect frequency of the drum and the endless track used in this drying process. Preferably, the surface defect frequency of 30 micrometers or more is 0.001-0.02 piece / mm <2>, More preferably, it is 0.002-0.015 piece / mm <2>.

The film after the dry process is peeled off from the support and introduced into the wet process, where the solvent and impurities contained in the film are removed. This bath generally consists of an aqueous medium and may contain an organic solvent, an inorganic salt, etc. in addition to water. However, generally, the moisture content is 30% or more, Preferably it contains 50% or more, and the thing of 0-100 degreeC of bath temperature is used normally.

Moreover, in order to reduce the impurity in a film, it is effective to raise a bath temperature to 50% or more, or to install the bath of an organic material, and to let it pass through it. Examples of the organic solvent include halogenated hydrocarbons such as chloroform, methylene chloride and freon, and organic solvents such as alcohol, ketone and ether. In this wet process, the peeled film is tensioned and immersed in such a bath, and the impurities in the film are extracted to 0.5% or less, preferably 0.2% or less, and more preferably 0.1% or less.

The film which has undergone the wet process is stretched, dried, and heat treated again to form a film.

Although the film formed as mentioned above is extended | stretched so that a mechanical characteristic may become the range of this invention in the film forming process, extending | stretching magnification is 0.8-8.0 by surface magnification (drawing area stretches the film area after extending | stretching). It is defined as the value divided by the former film area.1 or less means relaxation), It is 1.1-5.0 more preferably. Moreover, it is effective to cool the film after extending | stretching or heat processing gradually, and to cool at the speed of 100 degrees C / sec or less is effective.

And the film of this invention may be a laminated film. For example, in the case of two layers, the superposition | polymerization of the aromatic polyamido solution is divided into two, each adds another particle, and is laminated | stacked, and also in the case of three or more layers. As a method of these lamination | stacking, there exist a well-known method, for example, lamination | stacking in a metal mold | die, lamination | stacking in a composite tube, the method of forming one layer once, and forming another layer on it.

Next, a magnetic layer is formed on this film. The method of forming the magnetic layer may be any of the wet method and the dry method described above. For example, when it is a wet method, the method of apply | coating a magnetic layer can be performed by a well-known method, but the method of using a Guavialol roll is more preferable at the point of uniformity of a coating film. As for the drying temperature after application | coating, 90 degreeC-150 degreeC is preferable. Moreover, it is preferable to perform a calendar process in the range of 25 degreeC-150 degreeC.

Thereafter, the back coat layer may be provided by a known method in order to improve the running property on the surface opposite to the magnetic layer.

In addition, the film coated with the magnetic layer is cured and then cut into a magnetic recording medium of the present invention. For example, but not limited to general use such as 8mm, professional use, broadcasting stations such as D-1, 2, 3, data use such as DDS-2, 3, 4, QIC, data 8mm, but is not limited thereto. .

Next, the measuring method and evaluation crime prevention in the present invention will be described.

(1) Number of surface coarse protrusions (H1, H2, H3)

The foreign material is observed and displayed by polarized light by a stereo microscope in the magnitude | size of the film surface of 100 cm <2>. The height of the marked foreign material is observed using a multiinterferometer at a wavelength of 546 nm, and the number of rings of the interference arc is examined. The number of things more than a single ring is H1, the number of things more than a bicyclic ring is H2, and the number of things more than a normal ring was made H3.

(2) Young's modulus

It measured using the Instron type tensile tester. The sample had a width of 10 mm, a length of 50 mm, a pulling speed of 300 mm / minute, and a measurement temperature of 20 ° C and 100 ° C.

(3) dimension change rate

Put the marks on the film at 150mm intervals, cut them into 10mm widths, and measure the sample. The thickness is measured in micrometers, weighed so that the load is 1 kg / mm 2, heated in an oven at 100 ° C. for 10 minutes, and the rate of dimensional change is calculated by the following equation.

(4) electron conversion characteristics

The film to which the electron layer was apply | coated was cut to 1/2 inch width, it was assembled to the VTR cassette, and it was made into the VTR tape. Using a home VTR on this tape, the chromar S / N was measured with a color video noise meter on a 100% chromar signal with a television test waveform generator. On the basis of a commercially available tape, it was determined that S / N was more than or less and x was less than or equal to one.

(5) runability

The film was cut into a tape with a width of 1/2 inch, and was run at 40 ° C and 80% RH using a tape running tester SFT 700 (manufactured by Yokohama Systems Research Institute). Obtained by

Where T1 is input tension and T2 is output tension. The guide diameter is 6 mmφ, the guide material is polyoxymethylene (surface roughness of 20 to 40 nm), the winding angle is 90 °, the running speed is 3.3 cm / sec, and the repeat stroke is 15 cm. When the μk obtained by this measurement was 0.35 or less, the runability was ○, and when exceeding 0.35, the runability was determined as x. This μk is a critical point that influences the controllability when the film is processed for magnetic recording materials, capacitors, packaging, and the like.

Example

In the following example, the present invention is described with reference to Examples, but the present invention is not limited thereto.

Example 1

N-methylpyrrolidone (NMP) is dissolved in 2-chloroparaphenylenediamine equivalent to 80 mol% as an aromatic diamine component and 4.4-diaminodiphenyl ether corresponding to 20 mol%. 2-Chloro terephthalate equivalent of mol% was added, and stirred for 2 hours to complete the polymerization. This was neutralized with lithium hydroxide to obtain an aromatic polyamide solution having a polymer concentration of 10% by weight and a viscosity of 3000 poise (unit of viscosity). To this solution, 2 wt% of dry silica having a primary particle diameter of 16 nm, a secondary particle diameter of 0.2 µm, and the like were added per polymer.

The polymer solution was passed through a 5 μm filter, and the frequency of surface crystals having a diameter of 30 μm or more was stretched on a belt of 0.006 pieces / mm 2, heated by 180 ° C. hot air for 2 hours, and the solvent was evaporated. The obtained film was continuously removed from the belt. Subsequently, the film was placed in a water bath having a concentration gradient of NMP, and the remaining solvent and water of the inorganic salt formed by neutralization were extracted, followed by drying and heat treatment of water in a tenter to obtain an aromatic polyamide film having a thickness of 6 µm. In the meantime, the film was stretched 1.2 times and 1.3 times in the film length direction and the width direction, respectively, and after drying and heat treatment at 280 ° C. for 1.5 minutes, was gradually cooled at a rate of 20 ° C./sec.

The number of surface coarse protrusions on the surface of the film not in contact with the belt was 20/100 cm 2 and H1 was 45/100 cm 2, and the number of surface coarse protrusions on the belt contact surface was 40/100 cm 2. . As for the tensile Young's modulus (E20) in 20 degreeC of this film, the ratio with the tensile Young's modulus (E100) in 1250 kg / mm <2> and 100 degreeC in the longitudinal direction width direction was E100 / E20 = 0.72 in the longitudinal direction and the width direction. Moreover, the dimensional change rate was 0.6% at the load of 1 kg / mm <2> of this film.

Next, the running property and the electron change characteristic of the film were measured, and both were satisfactory.

Example 2

As in Example 1, the polymer was passed through a 5 μm cut filter, and the frequency of surface defects with a diameter of 30 μm or more was stretched on a belt of 0.002 pieces / mm 2, and heated for 2 minutes by hot air at 200 ° C. to evaporate the solvent. The film that retained the fat was continuously removed from the belt. Thereafter, an aromatic polyimide film having a thickness of 5 μm was obtained in the same manner as in Example 1.

The number of surface coarse protrusions on the surface of the film not in contact with the belt was 30/100 cm 2 and H1 was 60/100 cm 2, and the number of surface coarse protrusions on the belt contact surface was 5/100 cm 2. . The tensile Young's modulus (E20) of this film was 1280 kg / mm <2> in the longitudinal direction and the width direction in 20 degreeC, and the ratio with the tensile Young's modulus (E100) in the longitudinal direction and the width direction was E100 / E20 = 0.70 in 100 degreeC. Moreover, the dimensional change rate was 0.6% at the load of 1 kg / mm <2> of this film.

Next, the runability and the electron conversion characteristics of the film were measured, and both were satisfactory.

Example 3

An aromatic polyamide film having a thickness of 5 μm was obtained in the same manner as in Example 1 except that the stretching of the film was 1.1 times in the longitudinal direction and 1.45 times in the width direction.

The number of surface coarse protrusions on the surface of the film not in contact with the belt was 20/100 cm 2 and H1 was 45/100 cm 2, and the number of surface coarse protrusions on the belt contact surface was 40/100 cm 2. . The tensile Young's modulus in the longitudinal direction at 20 ° C. of the film is 900 kg / mm 2 and the Young's modulus in the width direction is a film extended in the width direction of 1640 kg / mm 2, and the ratio with the tensile Young's modulus (E100) at 100 ° C. is It was 0.75 and 0.70 in the longitudinal direction and the width direction, respectively. Moreover, the dimensional change rate was 0.6% in the 1 kg / mm <2> load of a film.

Next, the runability and the electron conversion characteristics of the film were measured, and both were satisfactory.

Example 4

Paraphenylenediamine equivalent to 60 mol% and 4.4'-diaminodiphenyl ether equivalent to 40 mol% are dissolved in NMP as an aromatic diamine component, 2-chlorotelephthalate equivalent to 100 mol% Was added and stirred for 2 hours to complete the polymerization. This was neutralized with lithium hydroxide to obtain an aromatic polyamide solution having a polymer concentration of 10% by weight and a viscosity of 3000 poise. To this solution, 2 wt% of dry silica having a primary particle diameter of 16 nm and a secondary particle diameter of 0.2 µm was added per polymer.

The polymer solution was passed through a 5 μm cut filter, and the surface defects having a diameter of 30 μm or more were spread on a belt of 0.015 pieces / mm 2, heated with a hot air at 180 ° C. for 2 minutes to evaporate the solvent, The obtained film was continuously rolled out from the belt. Hereinafter, an aromatic polyamide film having a thickness of 5 μm was obtained in the same manner as in Example 1.

The number of surface coarse protrusions on the surface of the film not in contact with the belt was 20/100 cm 2 and H1 was 45/100 cm 2, and the number of surface coarse protrusions on the surface in contact with the belt was 75/100 in H 3. Cm 2. The tensile Young's modulus (E20) of this film was 920 kg / mm <2> in the longitudinal direction and the width direction, and the ratio with the tensile Young's modulus (E100) in 100 degreeC was E100 / E20 = 0.57 in both the longitudinal direction and the width direction. Moreover, the dimensional change rate in the load of 1 kg / mm <2> of this film was 1.1%.

Next, when the running property and the electron conversion characteristic of this film were measured, all were favorable.

Example 5

A 2-chloroparaphenylenediamine solution corresponding to 100 mol% is dissolved in NMP as an aromatic diamine component, and 3,3 ', 4,4'-biphenyltetracarboxylic acid equivalent to 100 mol% is added thereto. And polymerization to obtain a polyamic acid solution. To this solution was added 2 wt% of dry silica having a primary particle size of 16 µm per polymer.

The polymer solution was passed through a 5 μm cut filter, and the frequency of surface defects with a diameter of 30 μm or more was stretched on a belt of 0.006 pieces / mm 2, dried until it had self-maintainability by hot air at 150 ° C., and continuously from the belt. Kicked off. Next, after heat-processing in the 420 degreeC denter, it cooled gradually at the speed of 20 degree-C / sec. The draw ratio was 1.1 times in length and width and 6 micrometers in thickness.

The number of surface coarse protrusions on the surface of the film not in contact with the belt was 15/100 cm 2 in H2 and 40/100 cm 2 in H1. The number of surface coarse protrusions on the surface in contact with the belt was 55 in H3. 100 cm 2. The tensile Young's modulus (E20) of this film was 880 kg / mm <2> in the longitudinal direction and the width direction in 20 degreeC, and the ratio with the tensile Young's modulus (E100) in the longitudinal direction and the width direction was E100 / E20 = 0.85 in 100 degreeC. Moreover, the dimensional change rate was 0.6% at the load of 1 kg / mm <2> of this film.

Next, both the runability and the electron conversion characteristics of the film were measured.

Comparative Example 1

The same polymer as in Example 1 was passed through a 5 μm cut filter, and the frequency of surface defects having a diameter of 30 μm or more was stretched on a belt of 0.006 pieces / mm 2, and the solvent was evaporated by hot air at 230 ° C. to obtain self-maintainability. The film was continuously peeled off the belt. Thereafter, an aromatic polyamide film having a thickness of 5 µm was obtained in the same manner as in Example 1.

The surface coarseness on the surface of the film not in contact with the belt was H2 at 70/100 cm2, H1 was 130/100 cm2, and the surface coarseness at the contact surface with the belt was H3 at 40. 100 cm 2. The tensile Young's modulus (E20) of this film in 20 degreeC was 1230 kg / mm <2> in the longitudinal direction and the width direction, and the ratio with the tensile Young's modulus (E100) in 100 degreeC was E100 / E20 = 0.69 in the longitudinal direction and the width direction. Moreover, the dimensional change rate was 0.6% at the load of 1 kg / mm <2> of this film.

Next, it was good to measure the runability of this film, but it was poor when there were many coarse protrusions when measuring the electron conversion characteristic.

Comparative Example 2

After passing the same polymer as Example 1 through a 5 micrometer cut filter, the frequency of the surface defect of 30 micrometers or more spreads on the belt of 0.0001 piece / mm <2>, and the aromatic poly of 5 micrometers in thickness was carried out similarly to Example 1 An amide film was obtained.

The number of surface coarse protrusions on the belt non-contacting surface of this film was 15/100 cm 2, H1 was 35 / cm 2, and the number of surface coarse protrusions on the belt contacting surface was 1/100 cm 2. The tensile Young's modulus (E20) of this film was 1250 kg / mm <2> in the longitudinal direction and the width direction, and the ratio with the tensile Young's modulus (E100) in 100 degreeC was E100 / E20 = 0.72 in both the longitudinal direction and the width direction. Moreover, the dimensional change rate was 0.6% at the load of 1 kg / mm <2> of this film.

Next, the electron conversion characteristics of the film were measured, but it was good.

Comparative Example 3

After passing the same polymer as Example 1 through a 5 micrometer cut filter, the frequency of surface defects whose diameter is 30 micrometers or more spreads on the belt of 0.025 piece / mm <2>, and the aromatic polysilicon 5 micrometers thick was carried out by the same method as Example 1. An amide film was obtained.

The number of surface coarse protrusions on the belt non-contacting surface of this film was 20/100 cm 2, H1 was 50/100 cm 2, and the number of surface coarse protrusions on the belt contacting surface was 160/100 cm 2. The tensile Young's modulus (E20) of this film in 20 degreeC was 1250 kg / mm <2> in a longitudinal direction and the width direction, and the ratio with the tensile Young's modulus (E100) in 100 degreeC was E100 / E20 = 0.72 in a longitudinal direction and a width direction. Moreover, the dimension change rate of this film was 0.6% at the load of 1 kg / mm <2>.

Next, when the runability of this film was measured, it was good, but when the electron conversion characteristic was measured, it was bad.

Comparative Example 4

Paraphenylenediamine equivalent to 50 mol% and 4.4-diaminodiphenyl ether equivalent to 50 mol% are dissolved in NMP as an aromatic diamine component, and pyromeric acid anhydride equivalent to 100 mol% is added to this. And the polymerization was carried out to obtain a polyamic acid. To this solution, 2 wt% of dry silica having a primary particle size of 16 nm was added per polymer.

After passing this polymer solution through a 5 micrometer cut filter, the frequency of surface defects of 30 micrometers or more in diameter extends to the upper part of a belt of 0.006 piece / mm <2>, and it drys until it has self-maintainability by hot air of 180 degreeC, and removes from a belt. It peeled continuously. Next, after heat-processing with the 420 degreeC denter, it cooled gradually at the speed of 20 degree-C / sec. The draw ratio was 1.1 times both in length and width, and the thickness was 8 mu m.

The number of surface coarse protrusions on the non-belt surface of the film was 20/100 cm 2, H1 was 45/100 cm 2, and the number of surface coarse protrusions on the belt contact surface was 50/100 cm 2. The tensile Young's modulus (E20) of this film was 420 kg / mm <2> in the longitudinal direction, and 430 kg / mm <2> in the width direction, and the direction of 35 degrees clockwise from the width direction was the maximum at 450 kg / mm <2>. The ratio of tensile Young's modulus (E20) at 20 degreeC and tensile Young's modulus (E100) at 100 degreeC was E100 / E20 = 0.80 in the direction of 35 degreeC clockwise from the longitudinal direction, the width direction, and the width direction. Moreover, the dimensional change rate was 0.6% at the load of 1 kg / mm <2> of this film.

Next, the electron conversion characteristics of the film were measured, but good, but the running performance was not good.

Comparative Example 5

4,4-diaminodiphenylmethane equivalent to 100 mol% is dissolved in N-metalpyrrolidone (NMP) as an aromatic diamine component, and equivalent to 50 mol% isophthalate and 50 mol% Telephthalate was added and stirred for 2 hours to complete the polymerization. This was neutralized with lithium hydroxide to obtain an aromatic polyamide solution having a polymer concentration of 10% by weight and a viscosity of 3000 poise. To this solution was added 2 wt% of dry silica having a primary particle size of 16 nm and a secondary particle size of 0.2 µm per polymer.

Using this polyma solution, an aromatic polyamide film having a thickness of 6 μm was obtained in the same manner as in the first example.

The number of surface coarse protrusions on the belt non-contacting surface of this film was 20/100 cm 2, H1 was 45/100 cm 2, and the surface coarsening on the belt contact surface was 40/100 cm 2. The tensile Young's modulus (E20) of this film was 900 kg / mm <2> in the longitudinal direction and the width direction, and the ratio with the tensile Young's modulus (E100) in 100 degreeC was E100 / E20 = 0.46 in both the longitudinal direction and the width direction. Moreover, the dimensional change rate was 2.2% in the load of 1 kg / mm <2> of this film.

Next, the runability of the film was measured, but it was poor.

Industrial use

The present invention utilizes the excellent heat resistance and high rigidity of an aromatic polyamide or an aromatic polyimide, and also defines surface characteristics, so that the magnetic recording medium has excellent running characteristics, durability, and output characteristics even under strict conditions such as high temperature and repeated driving. Can be provided.

Table 1

Claims (3)

In a magnetic recording medium made by providing a magnetic layer on one side of a base film made of an aromatic polyamide or an aromatic polyimide, a multi-interferometer is used at a wavelength of 546 nm in the surface coarsening on the surface on which the magnetic layer of the base film is formed. The number H2 of coarse protrusions of at least double rings when observed by using a multi-interferometer at the wavelength of 546 nm among the surface coarsenings on the surface of the non-magnetic material side was observed. The tensile Young's modulus (E20) in at least one direction at 20 ° C of the base film and the tensile Young's modulus (E100) in the same direction at 100 ° C are Magnetic recording medium, characterized in that to satisfy. In a magnetic recording medium made by providing a magnetic layer on one side of a base film made of an aromatic polyamide or an aromatic polyimide, a multi-interferometer is used at a wavelength of 546 nm in the surface coarsening on the surface on which the magnetic layer of the base film is formed. The number of coarse projections H2 of double rings or more as observed and the number of coarse projections H3 of triple ring or more when observed using a multi-interferometer at a wavelength of 546 nm of the surface coarsening on the surface of the nonmagnetic material side, , The number of coarse protrusions H1 having at least one monocyclic ring when observed using a multi-interferometer at a wavelength of 546 nm of the surface coarseness on the surface of the magnetic layer of the base film is formed. In addition, the tensile Young's modulus (E20) in at least one direction at 20 ℃ and the tensile Young's modulus (E100) in the same direction at 100 ℃ of the base film, Magnetic recording medium, characterized in that to satisfy. The magnetic recording medium according to claim 1 or 2, wherein the rate of dimensional change at 100 DEG C for 10 minutes when a load of 1 kg per 1 mm &lt; 2 &gt; of the base film is applied is 2% or less.